diff --git a/.eslintrc.es5.json b/.eslintrc.es5.json
index e13ffd91c0..ef25a45fd1 100644
--- a/.eslintrc.es5.json
+++ b/.eslintrc.es5.json
@@ -38,7 +38,6 @@
     "no-lonely-if": 0,
     "no-mixed-operators": 0,
     "eqeqeq": 0,
-    "space-in-parens": 0,
     "max-len": 0,
     "no-trailing-spaces": 0,
     "global-require": 0,
diff --git a/assets/js/src/jquery.serialize_object.js b/assets/js/src/jquery.serialize_object.js
index bd1583835a..984c2e5d54 100644
--- a/assets/js/src/jquery.serialize_object.js
+++ b/assets/js/src/jquery.serialize_object.js
@@ -28,7 +28,7 @@ define(
         coerce_types = { true: !0, false: !1, null: null };
 
       // Iterate over all name=value pairs.
-      $.each( this.serializeArray(), function (j, v) {
+      $.each(this.serializeArray(), function (j, v) {
         var key = v.name,
           val = v.value,
           cur = obj,
@@ -36,18 +36,18 @@ define(
 
           // If key is more complex than 'foo', like 'a[]' or 'a[b][c]', split it
           // into its component parts.
-          keys = key.split( '][' ),
+          keys = key.split(']['),
           keys_last = keys.length - 1;
 
         // If the first keys part contains [ and the last ends with ], then []
         // are correctly balanced.
-        if ( /\[/.test( keys[0] ) && /\]$/.test( keys[ keys_last ] ) ) {
+        if (/\[/.test(keys[0]) && /\]$/.test(keys[ keys_last ])) {
           // Remove the trailing ] from the last keys part.
-          keys[ keys_last ] = keys[ keys_last ].replace( /\]$/, '' );
+          keys[ keys_last ] = keys[ keys_last ].replace(/\]$/, '');
 
           // Split first keys part into two parts on the [ and add them back onto
           // the beginning of the keys array.
-          keys = keys.shift().split('[').concat( keys );
+          keys = keys.shift().split('[').concat(keys);
 
           keys_last = keys.length - 1;
         } else {
@@ -56,14 +56,14 @@ define(
         }
 
         // Coerce values.
-        if ( coerce ) {
+        if (coerce) {
           val = val && !isNaN(val) ? +val              // number
             : val === 'undefined' ? undefined         // undefined
             : coerce_types[val] !== undefined ? coerce_types[val] // true, false, null
             : val;                                                // string
         }
 
-        if ( keys_last ) {
+        if (keys_last) {
           // Complex key, build deep object structure based on a few rules:
           // * The 'cur' pointer starts at the object top-level.
           // * [] = array push (n is set to array length), [n] = array if n is
@@ -73,10 +73,10 @@ define(
           //   object or array based on the type of the next keys part.
           // * Move the 'cur' pointer to the next level.
           // * Rinse & repeat.
-          for ( ; i <= keys_last; i++ ) {
+          for (; i <= keys_last; i++) {
             key = keys[i] === '' ? cur.length : keys[i];
             cur[key] = i < keys_last
-              ? cur[key] || ( keys[i+1] && isNaN( keys[i+1] ) ? {} : [] )
+              ? cur[key] || (keys[i+1] && isNaN(keys[i+1]) ? {} : [])
               : val;
             cur = cur[key];
           }
@@ -85,11 +85,11 @@ define(
           // Simple key, even simpler rules, since only scalars and shallow
           // arrays are allowed.
 
-          if ( $.isArray( obj[key] ) ) {
+          if ($.isArray(obj[key])) {
             // val is already an array, so push on the next value.
-            obj[key].push( val );
+            obj[key].push(val);
 
-          } else if ( obj[key] !== undefined ) {
+          } else if (obj[key] !== undefined) {
             // val isn't an array, but since a second value has been specified,
             // convert val into an array.
             obj[key] = [ obj[key], val ];
diff --git a/assets/js/src/newsletter_editor/blocks/automatedLatestContent.js b/assets/js/src/newsletter_editor/blocks/automatedLatestContent.js
index 0b559c0eaa..470e68fd34 100644
--- a/assets/js/src/newsletter_editor/blocks/automatedLatestContent.js
+++ b/assets/js/src/newsletter_editor/blocks/automatedLatestContent.js
@@ -262,7 +262,7 @@ define([
           // Reset whole model in order for change events to propagate properly
           that.model.set('terms', terms.toJSON());
         }
-      }).trigger( 'change' );
+      }).trigger('change');
     },
     toggleDisplayOptions: function (event) {
       var el = this.$('.mailpoet_automated_latest_content_display_options'),
diff --git a/assets/js/src/newsletter_editor/blocks/image.js b/assets/js/src/newsletter_editor/blocks/image.js
index 55f7b819ee..f5d94264c8 100644
--- a/assets/js/src/newsletter_editor/blocks/image.js
+++ b/assets/js/src/newsletter_editor/blocks/image.js
@@ -253,7 +253,7 @@ define([
             editable: editable && function () {
               this.controller.content.mode('edit-selection');
             }
-          }).render() );
+          }).render());
         },
 
         mainInsertToolbar: function (view) {
diff --git a/assets/js/src/newsletter_editor/blocks/posts.js b/assets/js/src/newsletter_editor/blocks/posts.js
index f7f4f0af08..f282f0e8de 100644
--- a/assets/js/src/newsletter_editor/blocks/posts.js
+++ b/assets/js/src/newsletter_editor/blocks/posts.js
@@ -407,7 +407,7 @@ define([
           // Reset whole model in order for change events to propagate properly
           that.model.set('terms', terms.toJSON());
         }
-      }).trigger( 'change' );
+      }).trigger('change');
     },
     changeField: function (field, event) {
       this.model.set(field, jQuery(event.target).val());
diff --git a/assets/js/src/subscribers/importExport/import.js b/assets/js/src/subscribers/importExport/import.js
index 2cd80213a8..15d45ca007 100644
--- a/assets/js/src/subscribers/importExport/import.js
+++ b/assets/js/src/subscribers/importExport/import.js
@@ -331,7 +331,7 @@ define(
                   email = test[1].trim();
                 }
                   // test for valid characters using WP's rule (https://core.trac.wordpress.org/browser/tags/4.7.3/src/wp-includes/formatting.php#L2902)
-                if (!/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.\-@]+$/.test(email) ) {
+                if (!/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.\-@]+$/.test(email)) {
                   return false;
                 }
                 return email;